Short answer: For a gaming supplier-invoice workflow, the best LLM API for an in-app chatbot in Node.js is a currently available chat model such as deepseek-v4.1-flash behind /v1/chat/completions , with schema-shaped JSON and a small provider adapter. The important choice is the output contract, not the brand on the model.

The hard part is not getting text on the screen. It is keeping invoice_number , currency , line_items , and total stable when the model or backend changes. A conversational answer can be approximate. An accounting record cannot.

I would make the first implementation boring enough to test: stream the operator-facing reply, collect the extraction result, validate it in application code, and send anything ambiguous to review. That gives the chatbot a quick UI without letting a successful HTTP response become a trusted financial record.

Should this LLM API power a Node.js invoice chatbot?

Yes, if the API exposes a simple chat contract and the application owns validation.…